Ethyl Lactate and other lactate esters are environmentally benign, non-toxic solvents obtained from renewable carbohydrates via fermentation and separations processes. Ethyl lactate for example, has very good solvent properties and a characteristic odor.
Lactate esters can be blended with fatty acid esters and other ester containing solvents to provide biosolvent blends with enhanced solvating, cleaning and penetration properties. For example in U.S. Pat. Nos. 6,096,699 and 6,191,087 teach that lactate esters such as ethyl lactate blended with fatty acid esters such as methyl esters of soy oil fatty acids can be used for a variety of solvent cleaning, metal degreasing, paint and varnish removal applications. Allowed, co-assigned U.S. application Ser. No. 09/544,756 teaches that lactate esters and fatty acid esters can also be blended with dibasic esters such as dimethyl succinate, dimethyl adipate and glutarate and various surfactants to provide solvent cleaners that are particularly effective in cleaning printing machinery.
It has been noted that lactate esters can emit an odor whose perception and tolerance over time can inhibit commercial acceptance of products containing such esters. In some recent tests conducted with ethyl lactate solvent samples obtained from various manufacturers, it was found that the source and manufacturing processes did not have a significant impact on the odor perception. The test subjects, however, mentioned that the odor perception lingered and became more biting and irritating as the duration of their smelling increased. Anecdotal of an increase in the bite/irritation sensation with the duration of the use of lactate esters as well as other ester-based solvent blends have been reported. Thus, overcoming this irritation sensation could be important to the widespread acceptance of the lactate ester biosolvents.
Masking lactate ester solvent odor by addition of perfume components, by using citrus oil-based d-limonene and other solvent diluents has been attempted. In many cases such masking reduced the problem but only by a large amount of dilution of the lactate esters. However, because lactate esters have excellent solvating properties, dilution typically leads to reduction in performance. Furthermore, many applications require that the lactate esters be in high concentrations in the formulations. It would therefore be beneficial if the odors associated with the use of lactate esters could be abated or otherwise alleviated. The disclosure that follows provides one solution for alleviating the odors associated with lactate ester compositions.